Heterophase junction engineering-induced Co spin-state modulation of CoSe_(2) for large-current hydrogen evolution reaction

Efficient electrocatalysts are vital to large-current hydrogen production in commercial water splitting for green energy generation.Herein,a novel heterophase engineering strategy is described to produce polymorphic CoSe_(2)electrocatalysts.The composition of the electrocatalysts consisting of both cubic CoSe_(2)(c-CoSe_(2))and orthorhombic CoSe_(2)(o-CoSe_(2))phases can be controlled precisely.Our results demonstrate that junction-induced spin-state modulation of Co atoms enhances the adsorption of intermediates and accelerates charge transfer resulting in superior large-current hydrogen evolution reaction(HER)properties.Specifically,the CoSe_(2)based heterophase catalyst with the optimal c-CoSe_(2)content requires an overpotential of merely 240 mV to achieve 1,000 mA·cm^(-2)as well as a Tafel slope of 50.4 mV·dec^(-1).Furthermore,the electrocatalyst can maintain a large current density of 1,500 mA·cm^(-2)for over 320 h without decay.The results reveal the advantages and potential of heterophase junction engineering pertaining to design and fabrication of low-cost transition metal catalysts for large-current water splitting.

Modelisation and Optimization of a Microbial Desalination Cell System

In this work, we used a hybrid system composed of a Microbial Desalination Cell (MDC). This system allows, at the same time, the treatment of wastewater and the production of electrical energy for the desalination of saltwater. MDC is a cleaning technology used to purify wastewater. This process has been driven by converting organic compounds contained in wastewater into electrical energy through biological, chemical, and electrochemical processes. The produced electrical energy was used to desalinate the saline water. The objective of this work is the desalination or pre-desalination of seawater. For this, we have established a theoretical model consisting of differential equations describing the behavior of this system. Subsequently, we developed a program on MAT-LAB software to simulate and optimized the operation of this system and to promote the production of electrical energy in order to improve the desalination efficiency of the MDC. The theoretical result shows that the electrical current production is maximal when the methanogenic growth rate equal to zero, increases with the increasing of influent substrate concentration and the efficiency of desalination increased with flow rate of saline water.